The Food & Drug Administration on Monday barred the import of any medications made at the premier manufacturing plant of one of the world's largest makers of generic medications, Ranbaxy Laboratories Ltd.

The FDA cited Ranbaxy's failure to respond adequately to concerns it raised after two inspections of Ranbaxy's plant in Mohali, India, turned up shortcomings in manufacturing practices ensuring the quality of its products. Until Ranbaxy hires a third-party inspector and assures the FDA that its manufacturing standards are being met, the FDA said the company's products will remain under import alert and may be detained at the U.S. border.

Ranbaxy is a world power in the production of such generic medicines as the cholesterol-lowering drugs atorvastatin (marketed by Pfizer Inc. as Lipitor) and simvastatin (marketed as Zocor by Merck), the Alzheimer's disease drug donepezil (marketed as Aricept by Pfizer and Eisai) and the anti-viral drug valacyclovir (marketed as Valtrex by Glaxo Smith Kline). Ranbaxy's generic products are widely used in the U.S. marketplace.

The FDA said, however, that it does not expect medication supply disruptions or shortages as a result of its move, and urged patients to continue with their medication as prescribed by their physician.

The company touts its Mohali plant, built in India's Punjab region, as an "ultra-modern facility" that makes medications for export around the world. But in September 2012, and again in December 2012, the FDA turned up manufacturing problems that might result in the production of medications that were adulterated or inconsistent in dose or formulation. Ranbaxy failed to respond to the FDA's concerns with information about their root causes or how they should be addressed with production changes.

The FDA's move against Ranbaxy comes just four months after Ranbaxy pleaded guilty to federal drug safety violations and paid a $500-million fine to resolve claims that it sold substandard medications in the United States and made false statements to the FDA in the case. The U.S. Justice Department called the settlement the largest drug safety case in history against a generic drug manufacturer.

"The FDA is committed to using the full extent of its enforcement authority to ensure that drugs made for the U.S. market meet federally mandated quality standards," said Howard Sklamberg, director of the office of compliance in the FDA's Center for Drug Evaluation and Research. "We want American consumers to be confident that the drugs they are taking are of the highest quality, and the FDA will continue work to prevent potentially unsafe products from entering the country," he added.

[For the Record, Sept. 16, 10:00 p.m.: An earlier version of this post described Ranbaxy Laboratories Ltd. as the world's largest manufacturer of generics. It is one of the largest.]

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